Typical chain locks include generally a locking body and a chain or flexible wire which has one end connected with one side of the locking body and the other end has a plug lockable into a recessed latch in the other side of the body. The locking body may be an ordinary keyed lock, a safety lock or a combination lock. No matter whatever they are, they have the sane unlocking manner. When the lock is turned into an opening position, the plug of the chain will be ejected out of the locking body and therefore unlocked. This manner is well known and are not very burglarproof. However, the chain lock is useful nowadays. It not only locks a wheel of a motorcycle or a bicycle, a number of keys, but also a series of travelling certificates such as a passport, an air ticket, a boarding pass etc., so that an exquisite, reliable and portable chain lock is required.